Synchronization in semiconductor laser rings

We examine the dynamics of semiconductor lasers coupled in a ring configuration. The lasers, which have stable output intensity when isolated, behave chaotically when coupled unidirectionally in a closed chain. In this way, we show that neither feedback nor bidirectional coupling is necessary to induce chaotic dynamics at the laser output. We study the synchronization phenomena arising in this particular coupling architecture, and discuss its possible application to chaos-based communications. Next, we extend the study to bidirectional coupling and propose an appropriate technique to optical chaos encryption/decryption in closed chains of mutually coupled semiconductor lasers.Comment: 15 pages, 7 figure

Plantes transgèniques en recerca

El conjunt d'aproximacions presentades en aquest article il·lustra alguns dels usos més habituals de les plantes transgèniques en la recerca, que han permès, i encara permeten, respondre moltes preguntes genuïnes de gran interès biològic difícilment resolubles per altres aproximacions. Per això es pot afirmar que les plantes transgèniques han revolucionat la recerca bàsica i aplicada en el camp de la biologia vegetal. La seua utilització ens està ajudant a entendre millor com uns organismes tan fascinants i plàstics com les plantes es formen i, en interaccionar amb el medi, responen alterant la seua forma o fisiologia. Encara ens queda molt per conèixer, i l'ús de plantes transgèniques en la nostra recerca encara té molt a dir. Esbrinar més o menys depèn, en gran mesura, de la imaginació dels investigadors.The different strategies summarized in the manuscript illustrate some of the most common uses of transgenic plants in research. They have allowed answering several questions of great biological importance that cannot be easily addressed by other approaches. For that reason it is probably correct to state that transgenic plants have revolutionized basic and applied research in plant biology. Its utilization is helping us to better understand how these fascinating and plastic organisms are formed and, when interacting with the environment, responding by changing their form and/or physiology. We still have a lot to learn, and usage of transgenic plants in our research still has a lot to give. To discover more or less depends, partially, on the imagination of researchers

The influence of organochlorine compound exposure on the physiological development of children

The present study summarizes the advances on the knowledge of the health disturbances associated to fetal exposure to organochlorine compounds in a cohort of children from Menorca. Higher incidence of diverse deleterious health effects at 4 years of age have been observed, e.g. hexachlorobenzene (HCB) and poor social behavior and attention-deficit hyperactivity disorder, 4,4’-DDE and asthma, wheeze, lower respiratory tract infections and alteration of urinary coproporphyrins, HCB, ß-hexachlorocyclohexane and 4,4’-DDE and alteration of thyroid hormones, HCB, 4,4’-DDE and polychlorobiphenyls (PCBs) and overweight, 4,4’-DDT and PCBs and lower neurodevelopment. A protective effect of breastfeeding against decreases of cognitive skills in children due to 4,4’-DDT exposure has also been documented. This protective effect shows that other factors besides pollutant exposure and genetic variability influence on the health effects of environmental pollutants into human populations. These results are important for the understanding of the health implications of exposome studies.Aquest estudi resumeix els avenços en el coneixement dels trastorns de salut associats a l’exposició fetal a compostos organoclorats en una cohort de nens de Menorca. S’ha observat una incidència major de diversos efectes perjudicials per la salut als 4 anys d’edat, per exemple, hexaclorobenzè (HCB) i comportament social pobre i trastorn per dèficit d’atenció amb hiperactivitat, 4,4’- DDE i asma, xiulets pulmonars, infeccions de les vies respiratòries baixes i alteració de coproporfirines urinàries, HCB, ß-hexaclorociclohexà i 4,4’-DDE i alteració de les hormones tiroïdals, HCB, 4,4’-DDE i policlorobifenils (PCBs) i sobrepès, 4,4’-DDT i PCBs i menor desenvolupament neurològic. També s’ha documentat un efecte protector de la lactància materna contra la disminució de les habilitats cognitives dels nens a causa de l’exposició a 4,4’-DDT. Aquest efecte protector mostra que altres factors, a més de l’exposició a contaminants i genètica personal, influeixen en els efectes de salut dels contaminants ambientals en les poblacions humanes. Aquests resultats són importants per comprendre les implicacions per la salut dels estudis d’exposomes

Quantitative identification of dynamical transitions in a semiconductor laser with optical feedback

Identifying transitions to complex dynamical regimes is a fundamental open problem with many practical applications. Semi- conductor lasers with optical feedback are excellent testbeds for studying such transitions, as they can generate a rich variety of output signals. Here we apply three analysis tools to quantify various aspects of the dynamical transitions that occur as the laser pump current increases. These tools allow to quantitatively detect the onset of two different regimes, low-frequency fluctuations and coherence collapse, and can be used for identifying the operating conditions that result in specific dynamical properties of the laser output. These tools can also be valuable for analyzing regime transitions in other complex systems.Peer ReviewedPostprint (published version

Towards Efficient Incident Detection in Real-time Traffic Management

Incident detection is a key component in real-time traffic management systems that allows efficient response plan generation and decision making by means of risk alerts at critical affected sections in the network. State-of-the-art incident detection techniques traditionally require: i) good quality data from closely located sensor pairs, ii) a minimum of two reliable measurements from the flow- occupancy-speed triad, and iii) supervised adjustment of thresholds that will trigger anomalous traffic states. Despite such requirements may be reasonably achieved in simulated scenarios, real-time downstream applications rarely work under such ideal conditions and must deal with low reliability data, missing measurements, and scarcity of curated incident labelled datasets, among other challenges. This paper proposes an unsupervised technique based on univariate timeseries anomaly detection for computationally efficient incident detection in real-world scenarios. Such technique is proved to successfully work when only flow measurements are available, and to dynamically adjust thresholds that adapt to changes in the supply. Moreover, results show good performance with low-reliability and missing data

Light signaling: back to space

Recent work has increased our understanding of the molecular and cellular mechanisms of the phytochrome family of photoreceptors in controlling plant photomorphogenesis. However, the importance of long-distance communication in controlling light responses has received relatively little attention and is poorly understoodPostprint (author's final draft

Distinguishing signatures of determinism and stochasticity in spiking complex systems

Acknowledgements: This work was supported in part by grant FA8655-12-1-2140 from EOARD US, grant FIS2009-13360 from the Spanish MCI and grant 2009 SGR 1168 from the Generalitat de Catalunya. C. Masoller acknowledges partial support from the ICREA Academia programme. N. Rubido acknowledges the Scottish University Physics Alliance.Peer reviewedPublisher PD

LA ECONOMÍA DEL CONOCIMIENTO EN ESPAÑA: UNA COMPARACIÓN INTERNACIONAL DE SU DESARROLLO

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